Color Stability of the Bulk-Fill Composite Resins with Different Thickness in Response to Coffee/Water Immersion

Abstract

We aimed to evaluate the color stability of bulk-fill and conventional composite resin with respect to thickness and storage media. Twenty specimens of a conventional composite resin (6 mm diameter and 2 mm thick) and 40 specimens of the bulk-fill Tetric EvoCeram composite resin at two different thicknesses (6 mm diameter and 2 mm thick or 4 mm thick, n = 20) were prepared. The specimens were stored in distilled water during the study period (28 d). Half of the specimens were remained in distilled water and the other half were immersed in coffee solution 20 min/d and kept in distilled water between the cycles. Color changes (ΔE) were measured using the CIE L ⁎ a ⁎ b ⁎ color space and a digital imaging system at 1, 7, 14, and 28 days of storage. Data were analyzed using Two-way ANOVA and Tukey's HSD post hoc test (P < 0.05). Composite resins showed significant increase in color changes by time (bulk-fill > conventional; P < 0.001). Coffee exhibited significantly more staining susceptibility than that of distilled water (P < 0.001). There was greater color changes with increasing the increment thickness, which was significant at 14 (P < 0.001) and 28 d (P < 0.01). Color change of bulk-fill composite resin was greater than that of the conventional one after coffee staining and is also a function of increment thicknesses.

Color stability of bulk‐fill and universal composite restorations with dissimilar dentin replacement materials

“…Polishing was shown to partially reduce discoloration, hence suggesting two mechanisms of extrinsic discoloration, pigment absorption within the polymer matrix and pigment adsorption on material surface . Intrinsic discoloration due to hydrolytic changes in the polymer network seem to have a lesser effect on the overall discoloration as color differences after water storage were reported to be smaller compared to colored storage media . Changes in a * and b * showed less consistency in the tested cohort of composites, without a clear shift toward a specific color on the red‐green or blue‐yellow coordinates.…”

“…35 Intrinsic discoloration due to hydrolytic changes in the polymer network seem to have a lesser effect on the overall discoloration as color differences after water storage were reported to be smaller compared to colored storage media. 12,14,34,36 Changes in a* and b* showed less consistency in the tested cohort of composites, without a clear shift toward a specific color on the red-green or blue-yellow coordinates. Similar variable findings were reported in previous studies following material exposure to red wine.…”

“…An exception is a fiber-reinforced bulk-fill composite everX Posterior (GC) requiring a final layer of another composite due to its long glass fibers. Differences in color stability between bulk-fill and universal composites were found in staining media, albeit with inconclusive data, depending on composite brands, [12][13][14] layer thickness, 14 polishing procedures, 13 and staining media. 12 Dentin replacement materials with unfavorable esthetic properties, such as calcium-silicate cements (eg, Biodentine) and experimental hydroxyapatite (HAP) inserts, require a 2 mm thick capping composite layer to neutralize the effect of the underlying material on color and translucency.…”

“…An exception is a fiber‐reinforced bulk‐fill composite everX Posterior (GC) requiring a final layer of another composite due to its long glass fibers. Differences in color stability between bulk‐fill and universal composites were found in staining media, albeit with inconclusive data, depending on composite brands, layer thickness, polishing procedures, and staining media …”

Color stability of bulk‐fill composites immersed in different drinks

“…Studies have revealed that these composites can be applied and lightcured in one layer of 4 mm, with low polymerization shrinkage and a high degree of conversion, resulting in less chair time and less gap formation. [16][17][18][19] Polymerization problems are highly diminished according to the higher translucency of the resin materials, which allows for greater light transmission. 16 There are also structural differences between bulk-fill composites and composite resins.…”